President Trump arrives in Philadelphia on Jan. 26 to attend a Republican strategy retreat. (Nicholas Kamm/AFP/Getty Images)

President Trump pledged Thursday to “massively” lower taxes on the middle class, fix the country’s infrastructure, replace the “disaster” known as Obamacare and negotiate a series of one-on-one trade deals to supplant what he characterized as a current “big mash pot.”

The recitation of a long list of promises came during an address in Philadelphia at a Republican retreat, where the new president pledged to work shoulder-to-shoulder with the GOP-led Congress but offered few new specifics about his agenda.

“This Congress is going to be the busiest Congress we’ve had in decades, maybe ever,” Trump said in a large hotel ballroom filled with lunch tables and a packed crowd that interrupted him several times with applause. He opened his remarks by recounting his electoral victory in Pennsylvania.

Trump also told the lawmakers that the decision to cancel a planned bilateral meeting with Mexican President Enrique Peña Nieto was mutual, saying that moving ahead would have been “fruitless.”

“Unless Mexico is going to treat the United States fairly with respect, such a meeting would be fruitless and I want to go a different route,” Trump said. “We have no choice.”

The Mexican president announced hours before that he had canceled a planned visit to the White House amid outrage in Mexico about Trump’s efforts to start building a border wall.

Trump’s executive order this week to construct a wall was one of a flurry of actions taken during his fledgling presidency that he recounted to lawmakers in the room.

During his remarks, Trump derided current U.S. trade policy, including the nation's participation in the North American Free Trade Agreement with Mexico.

“I made clear to the government of Mexico that NAFTA has been a terrible deal, a total disaster for the United States from the inception,” Trump said. “It’s costing us as much as $60 billion a year from Mexico alone in a trade deficit. You say, ‘Who negotiates these deals?’ ”

Trump also recounted his action this week to formally pull out of the Trans-Pacific Partnership, a planned deal with 11 other nations along the Pacific Rim.

Trump said he believes in “fair trade” and plans to negotiate numerous “one-on-one” deals that would give the United States more flexibility in withdrawing from arrangements that don’t live up to expectations.

“They’ll be one-on-one deals,” Trump said. “They won’t be a whole big mash pot.”

Trump also pledged to move forward with an infrastructure package, the notion of which has generated limited enthusiasm among Republicans on Capitol Hill.

As a candidate, Trump pledged to mobilize anywhere from half a trillion to a trillion dollars to upgrade the nation’s aging roads, bridges and transportation hubs. He offered few details Thursday, but he said the priority would be given to fixing aging infrastructure.

“We’ll fix our existing product before we build anything new,” Trump said. “We will fix it first because we have a lot of things that are in bad shape.”

Trump again promised “bold tax reform that massively lowers taxes for our middle class and all American businesses.”

And he said that he looked forward to working with Republicans to repeal and replace the Affordable Care Act, a process he began with an executive order shortly after taking office.